RU2421276C2 - Tubular reactor for production of sulfur-containing nitrogen fertilisers - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to tubular reactor that comprises, at least, one inlet zone, at least, one mixing path, appliances to load first and second reagents arranged in, at least, one inlet zone, and, at least, one third appliance to load, at least, one third reagents arranged in, at least, one inlet zone or behind, at least, one mixing path.

EFFECT: higher process efficiency.

37 cl, 9 dwg, 3 ex

Description

The invention relates to a tubular reactor for implementing the method for producing sulfur-containing nitrogen fertilizers according to claim 1, to the method according to claim 24 and to the device according to claim 44 of the formula.

Natural phosphates are based on 75-80% by weight of the apatite mineral, which plants cannot use as a source of phosphates due to the significant water insolubility of this material. In order to convert natural phosphates into a form that is absorbed by plants, it is required to extract part of the calcium contained in the apatite mineral. For this, including the nitrophosphate method, also called the Odd method.

In the nitrophosphate method, after dissolving the natural phosphate with nitric acid in the Odd installation, calcium nitrate tetrahydrate precipitates out by filtration:

In recent years, in some areas, due to a decrease in sulfur emissions due to increased desulphurization of flue gases and a decrease in sulfur content in fuels, depletion of sulfur soils for agricultural purposes is observed. Extraction of sulfur by plants should be supplemented by the addition of sulfur through fertilizers. Demand for sulfur-containing fertilizers increased, in particular, for simple nitrogen fertilizers with sulfur.

One of the possible sulfur-containing components for the production of sulfur-containing fertilizers is gypsum. It is known that natural phosphate is dissolved not with nitric acid, but with sulfuric, and the precipitated gypsum and filtrate are processed into the desired products. This method is known as the wet acid method (US 3653872 or GB 1247365).

Methods are also known in which precipitated gypsum is used to produce sulfur-containing complex fertilizers. This is described, for example, in RU 2186751 and Winnacker Küchler "Chemische Technologie", Band 2, 4. Auflage, 1982, pp. 356-360.

These methods are inherent in the fact that due to the addition of sulfuric acid during the dissolution of natural phosphate, so-called precipitated gypsum occurs, which is then processed. The disadvantage is that the crystalline precipitated gypsum must be filtered before further processing, which is technically very difficult. Further, when gypsum falls out, hemihydrate or gypsum dihydrate occurs, which forms viscous pastes and therefore cannot be mixed with other components and granulated. In addition, the precipitated gypsum contains part of the heavy metal contaminants of natural phosphate. As a result, its scope is very limited; in most cases, the precipitated gypsum must be disposed of, which is increasingly associated with high costs.

A method for producing sulfur-containing nitrogen fertilizers is known from WO 2006/050936, in which calcium nitrate is converted in the mixer by a sulfur-containing compound, preferably sulfuric acid, H ₂ SO ₄ , and fertilizer is obtained by granulating the resulting gypsum-containing suspension. The conversion takes place here in a stirred ammonia reactor in the presence of ammonia NH ₃ .

In this case, the reagents are introduced into the reactor with a stirrer at the same time. The parallel introduction of reagents can lead to local overheating, since gaseous NH _{3 is} not dispersed sufficiently. A long residence time in an acidic environment and local overheating can in the worst case lead to explosions. Due to the relatively long residence time of the reactants in the reactor, the formation of a highly viscous mass occurs, which can cause displacements.

In addition to agitated reactors, tubular reactors are known in the field of fertilizer production. Thus, for example, the preparation of ammonium nitrate, nitrogen-phosphorus-potassium fertilizers or ammonium sulfate in a tubular reactor is described.

EP 0272974 describes, for example, a tubular reactor for neutralizing a phosphate dissolution product by introducing NH ₃ , whereby ammonium phosphate or polyphosphate is formed. In this case, NH ₃ , water, nitric acid and phosphorus oxide are introduced separately into a tubular reactor, where they react with each other.

Also from EP 2695840 a tubular reactor is known for neutralizing sulfuric or phosphoric acid by introducing NH ₃ . At the same time, a mixer is located in the input zone.

In preparing sulfur-containing nitrogen fertilizers in the form of a gypsum-containing suspension, in accordance with conventional methods, sulfuric acid H ₂ SO ₄ and ammonia NH ₃ would be mixed first, and the resulting ammonium sulfate would be converted with calcium nitrate. The problem with this reaction is, however, the strongly exothermic nature of the reaction of sulfuric acid and ammonia, as a result of which cooling with cooling water directly in the reactor is necessary.

Since, however, for better storage stability and processability, it is desirable to obtain an anhydrous fertilizer formula, it is not practical to cool the reaction mixture with water. To obtain anhydrous fertilizers, the water content in the reactor should not exceed 5-15%.

The basis of the invention is the creation of a reactor and a method for producing low-sulfur nitrogen fertilizers, in which strong heat generation and local overheating and the associated danger of explosion would be reduced or prevented without the need for direct cooling of the reaction medium with water.

This problem is solved by means of a tubular reactor with the features of claim 1 of the formula.

The tubular reactor has at least one inlet zone and at least one mixing path, with at least one first means for loading the first reactant and at least one second means for loading the second reagent. The tubular reactor contains at least one additional third means for loading an additional third reagent, the third means being located in at least one inlet zone, in and / or after at least one mixing path.

Moreover, it is preferable that the tubular reactor contains several means for loading a third reagent, one of these means being located in at least one inlet zone and the other of these means after at least one mixing path.

Preferably, the tubular reactor is modular and has, in addition to the mixing path, at least one inlet and at least one outlet zone, the mixing path being located between the inlet and outlet zones.

Preferably, the tubular reactor has at least two mixing paths, and at least one third means for loading the third reagent into the tubular reactor is located between at least two mixing paths.

At least one third means for loading the third reagent after the mixing path is preferably in the form of a bent loading pipe, the outlet of the loading pipe being located in the middle of the cross section of the tubular reactor. Due to this arrangement, at least one reagent, for example a sulfur-containing compound, is introduced directly into the calcium nitrate solution mixed with ammonia. This prevents the reaction with gaseous ammonia accumulated, in particular, in the upper part of the reactor.

Preferably, at least one third means for loading the third reagent into the tubular reactor serves to load ammonia.

It is also preferred that at least one third means for loading the third reagent into the tubular reactor serves to load a sulfur-containing compound, in particular sulfuric acid.

It is also possible that the third means for loading the sulfur-containing compound into the inlet zone of the tubular reactor. made of at least two parts, and the parts are located radially around the tubular reactor.

Preferably, at least the first means in the inlet zone serves for loading a solution of calcium nitrate, for example in the form of molten Ca (NO ₃ ) ₂ · 4H ₂ O, and at least the second means in the inlet zone for loading NH ₃ .

The tubular reactor thereby provides a separate reagent charge. In particular, the possibility of stepwise loading of ammonia as a second reagent prevents an exothermic reaction that is too strong, which prevents local overheating.

In addition, the tubular reactor provides a short residence time of the reagents and good mixing throughout the cross section of the apparatus. A high flow rate is also achieved, so that the reaction time is generally short.

The advantage of a tubular reactor compared to boilers with a stirrer is that it does not require any additional pumps for transporting the reaction mixture. Therefore, in a tubular reactor, reagents are transported through a pipe with a certain inlet pressure, while in a boiler with a stirrer, a pump is needed for transporting sulfur-containing fertilizer.

Preferably, the tubular reactor comprises in the inlet zone at least one mixing head, in particular a cascade mixing head, and preferably at least one static mixer, in particular an intensive one, is located in it.

To disperse ammonia in a solution of calcium nitrate in the inlet zone, it is preferable to use an intensive mixer instead of spiral mixing elements, as a result of which the total length of the tubular reactor is reduced.

Preferably, if the first means for loading the first reagent is made in the form of an inlet pipe with a diameter of up to 40 mm, and the second means for loading the second reagent is in the form of an inlet pipe, in particular curved, with a diameter of up to 150 mm.

In particular, it is preferable if the first and second means for loading the first and second reagents are located at an angle of 0-90 °, preferably 90 °, to the axis of the tubular reactor. It is also preferred that the first and second means are located at an angle of 0-180 °, preferably 90 °, with respect to each other.

It is also preferred that at least one static mixing element is located on at least one mixing path. This element, at least on one mixing path of the tubular reactor, is preferably made in the form of a mixing element with means for changing the direction of rotation, in particular in the form of a spiral mixer, means for swirling, in particular an intensive mixer, and / or a static mixer.

In particular, it is preferable if the mixing path is equipped with several mixing elements, in particular spiral ones. Moreover, the mixing elements are preferably located in at least one of the two sections of the mixing path, with the preferred location after the means for loading the sulfur-containing compound.

Preferably, two or more spiral mixing elements are arranged on the mixing path in the opposite direction of rotation in order to achieve optimum mixing of the reactants. Spiral mixing elements are made so that, if necessary, they can be easily removed from the tubular reactor and replaced. In addition, spiral mixing elements have the advantage that they can be manufactured inexpensively and quickly.

The mixing path preferably has a diameter of up to 300 mm, in particular 50-250 mm, and a total length of up to 5500 mm, in particular up to 4000 mm. These sizes at the corresponding expense provide turbulent flow in a tubular reactor. The Reynolds number ideally has a value of 2000-2500.

Diameter over 300 mm is not recommended for safety reasons. A total length in excess of 5500 mm is also not recommended, since this leads to unnecessary pressure loss in the tubular reactor and poses a risk of displacements due to the reaction product.

Preferably, the outlet zone of the tubular reactor is directed to a granulation drum. The exit zone preferably has at least one nozzle and / or at least one restriction and / or at least one conical restriction. In this way, pressure fluctuations in the reactor are prevented. In addition, the release of water vapor in the reactor is prevented, and good atomization of the product is achieved by constriction.

In one preferred embodiment of the reactor, the transition to the granulation drum occurs through a two-component nozzle. In this case, the narrowing at the transition to the granulation drum is formed by two concentric pipes, with the inner pipe in the direct continuation of the reactor connected to it with a geometric closure, and the outer pipe through the annular pipe with connecting fittings for compressed air is located on the inner pipe with the possibility of longitudinal movement, protruding for it along the length and due to a steeper narrowing angle relative to the inner pipe provides a variable distribution of compressed air at its mouth, so that when due to this dispersion, load the product through a two-component nozzle made in this way into a granulation drum with different fineness.

Preferably, if the tubular reactor is operated continuously and is located in front of the granulation unit. Particularly preferred is a device for separating the resulting water vapor from the reaction product. Thus, a tubular reactor can be located, for example, at the rear end of a granulation drum operated in a direct flow. This device ensures that at the outlet of the drum, the released water vapor is immediately aspirated with exhaust air from the granulation drum and longer contact with the product is prevented. Similarly, it is preferable if the tubular reactor is directed into the granulation unit in the form of a two-bladed screw. It is possible to remove the released water vapor in the two-blade screw, which does not interfere in the adjacent granulation or drying unit.

Between the mixing path and the exit zone are located a means for sampling, in particular in the form of a tee, an additional means for introducing air, a means for determining the temperature.

The objective of the invention is also solved by a method for producing low-sulfur nitrogen fertilizers according to paragraph 24 and by using a tubular reactor in the implementation of this method.

A method for producing sulfur-containing nitrogen fertilizers includes the conversion of calcium nitrate tetrahydrate to a sulfur-containing compound in a tubular reactor, as well as subsequent ganulation of the resulting gypsum-containing suspension.

Thus, even doughy suspensions with a low water content can be mixed with other components and processed in traditional granulators. The method is simple primarily because it allows you to do without the technically complex separation of precipitated gypsum that occurs when natural phosphate is dissolved.

Calcium nitrate may be used in any form, for example, as a commercially available aqueous solution. You can also use calcium nitrate obtained by the reaction of CaCO ₃ with NHO ₃ .

However, it is particularly preferred if the calcium nitrate tetrahydrate used in the production of complex fertilizers is calcium nitrate tetrahydrate obtained by the nitrophosphate process. Thus, the calcium contained in natural phosphate can be used to produce more and more required sulfur-containing nitrogen fertilizers.

The sulfur source can be any sulfur compound, for example magnesium or ammonium sulfate. Preferably, however, sulfuric acid is used as the sulfur compound. It is preferable because it is easier to handle as a liquid than with solid sulfates.

The conversion takes place preferably in the presence of ammonia, usually used in gaseous form. However, liquid ammonia or ammonia water may also be used.

If calcium nitrate is converted by sulfuric acid and ammonia in a tubular reactor, then very good mixing is achieved. The neutralization reaction takes place, and due to the heat of neutralization formed, the transformation occurs at about boiling point. High temperature during the conversion is preferable because, thus, a suspension with anhydrous gypsum anhydrite occurs. Gypsum anhydrite is desirable primarily because it has very good granulation properties. A pumpable gypsum-containing suspension with a low water content is obtained.

The method includes the following reactions:

Reaction (2) is the main reaction in a tubular reactor and leads to the formation of up to 46% anhydrous gypsum in the reaction product. Water of calcium nitrate tetrahydrate evaporates due to the exothermic reaction at a temperature at which the resulting gypsum is dehydrated.

Obtaining anhydrous gypsum is of great importance, since only it guarantees a high content of nutrients in the final fertilizer. Therefore, it is required that all or approximately all of the amount of water introduced into the reactants evaporates due to the exothermic reaction. The reaction product contains water, preferably 10% or less. If there is more water in the reaction product, then anhydrous gypsum anhydrite reacts upon cooling to a water-containing hemihydrate or gypsum dihydrate, and gypsum with too high a proportion of water is obtained, so that the desired fertilizer formula will no longer be obtained.

In reaction (3), all or part of nitric acid formed in reaction (2) is converted to ammonium nitrate. Thus, up to 54% ammonium nitrate can be achieved in the reaction product.

Ammonium nitrate can be increased if ammonium nitrate is either introduced into the tubular reactor or fed separately to the granulation drum. However, it is not recommended to increase the content of ammonium nitrate in the tubular reactor, since an explosive mixture may occur.

The reaction (4) is preferably limited to a total fraction of 3-5 wt.%, Since the reaction is very endothermic and the temperature rises very much, which leads to problems of corrosion of the material.

In particular, it is preferable if a calcium nitrate solution is used with a calcium nitrate content of 55-65%, in particular 60%. The calcium nitrate solution thus has a water content of 35-45%, preferably 40%.

This is especially important since the water content of the reaction mixture depends on the quality of the calcium nitrate tetrahydrate used. A 55% solution of calcium nitrate contains relatively much water, which, however, leads to a calm reaction in a tubular reactor. However, the water content is so great that not all water can evaporate due to the heat of reaction, as a result of which the nutrient content in the fertilizer will be too low.

A 65% solution of calcium nitrate containing less water, however, leads, on the other hand, to an optimal product, however, the viscosity due to the lower water content is high, which can cause problems during operation of the reactor. The optimal compromise is therefore the use of a 60% solution of calcium nitrate.

The loading of the reagents into the tubular reactor preferably takes place in several stages. At the first stage a) reagents, a solution of calcium nitrate and NH ₃ are loaded into the inlet zone of the tubular reactor and mixed in the mixing head. At the second stage b), sulfuric acid is loaded into the tubular reactor in the inlet zone, into the mixing path or after the mixing path, and in the next mixing path a gypsum-containing suspension is formed.

You can also load reagents simultaneously or in the first stage, first sulfuric acid and calcium nitrate, and then ammonia.

The loading of NH ₃ into the inlet zone occurs at the first stage a), preferably parallel to the axis of the tubular reactor, and the loading of calcium nitrate tetrahydrate at an angle of 90 °. However, it is also possible that the loading of ammonia into the inlet zone occurs at the first stage a) at an angle less than 90 ° to the axis of the tubular reactor, and the loading of calcium nitrate tetrahydrate parallel to its axis.

The method is preferably characterized in that in the third step c) additional ammonia is charged into the tubular reactor after at least one mixing path, i.e. Ammonia loading occurs in two parts. In this case, preferably at least 2/3 is loaded in the first step a), and at least 1/3 of the total amount of ammonia required in the third step c) is loaded. The loading of additional ammonia is possible in the granulation drum to set the pH to a value greater than 4.5.

Preferably, the calcium nitrate solution is charged into the inlet zone as a solution and mixed with ammonia therein by means of a static mixer, in particular an intensive mixer. As a result, ammonia is dispersed uniformly in the form of small bubbles in a solution of calcium nitrate.

Within the mixing path, mixing with sulfuric acid takes place preferably by means of mixing elements, in particular by means of a spiral mixer. Spiral mixers are especially suitable for viscous, anhydrous, gypsum-containing suspensions, since when using this type of mixer, a large cross-section of the pipe remains free and, thereby, the risk of deposits on the walls of the reactor is minimized.

The reaction temperatures in the tubular reactor are 120-145 ° C, preferably 130-140 ° C. The reaction pressure in the tubular reactor is 250,000-600,000 Pa, preferably 250,000-350,000 Pa during the process. Thus, the reaction pressure corresponds to the vapor pressure of the water present in the tubular reactor. The temperature and pressure can be arbitrarily varied by introducing condensate, in particular water, into the tubular reactor. So, for example, when condensate is introduced, both the temperature and the pressure decrease.

It is also preferred that if air is introduced into the tubular reactor after the mixing path and / or between the mixing path and the outlet zone. Air inlet ensures good atomization of the reaction product even at low flow rates, which is necessary for a good granulation process.

Preferably, ammonium nitrate is added to the calcium nitrate before conversion and / or during the conversion and / or before granulation. It can be added preferably in the form of an aqueous solution before the conversion of calcium nitrate to the sulfate compound. At the same time, it mixes with calcium nitrate before it reacts with sulfate. Thus, better solubility of calcium nitrate is achieved.

Next, you can add a solution of ammonium nitrate directly during conversion by sulfate or before granulation of fertilizer. The concentration of the added solution of ammonium nitrate is, for example, 64 or 94 wt.%. Ammonium nitrate can also be used in the form of a melt.

If only nitrogen-containing components are added, then a sulfur-containing nitrogen simple fertilizer is obtained, for example, such as “ammonium nitrate with sulfur”, “ammonium nitrate” or “nitrogen-magnesium”.

Further, other components may be added as nitrogen, for example, potassium salts, phosphoric salts, magnesium salts or other conventional fertilizer additives. Thus, a sulfur-containing complex fertilizer is obtained.

In one particularly preferred embodiment, the method is carried out continuously and integrated into the installation for the continuous production of complex fertilizers by the nitrophosphate method with two ammonization lines. In this case, the nitrophosphate plant can also be a plant producing sulfur-containing complex fertilizers, for example, by adding sulfuric acid during the ammonization of nitrophosphoric acid. Typically, a plant for producing calcium-ammonium nitrate from calcium nitrate tetrahydrate is associated with a nitro-phosphate plant.

Thus, it is possible in a simple way to obtain sulfur-containing nitrogen fertilizer as an accompanying product of complex fertilizers. The advantage is that there is no need, as in traditional methods, for the technically extremely complex separation of the precipitated gypsum. Since gypsum deposition according to the invention only occurs after the phosphate has been dissolved, separation is not necessary, and the resulting gypsum-containing suspension, due to its easy pumping and spraying capabilities, possibly after mixing other components, can be further processed directly into granulate.

Particularly preferred is the embodiment in which a plant for producing calcium ammonium nitrate from calcium nitrate tetrahydrate is associated with a nitrophosphate plant, and a sulfur-containing nitrogen fertilizer in this plant is obtained by converting calcium nitrate tetrahydrate with sulfuric acid in a tubular reactor.

A plant for the production of lime-ammonium nitrate usually contains a granulation block, which can be used to granulate a gypsum-containing suspension. Thus, by installing only one tubular reactor in an existing nitrophosphate plant or a plant for the production of calcium ammonium nitrate, without expensive and time-consuming conversion work, selectively calcium ammonium nitrate or sulfur-containing nitrogen fertilizer can be produced from precipitated calcium nitrate.

In one preferred embodiment, a sulfur-containing nitrogen fertilizer is obtained in a nitrophosphate installation with two ammonization lines containing at least one tubular reactor for neutralizing nitrophosphoric acid by converting calcium nitrate tetrahydrate with sulfuric acid in a tubular reactor. While preferably parallel to each other are several tubular reactors, at least two.

This option is carried out, for example, in a nitrophosphate installation with two Odd lines, two ammonization lines and two granulation lines. While one line is used in the traditional way to produce complex fertilizers, the second ammonization line does not work, and the second granulation line and the tubular reactor are used to produce sulfur fertilizers. You can also implement the method in nitrophosphate plants containing more than two lines of ammonization and granulation. Usually, a plant for producing lime-ammonium nitrate is associated with a nitrophosphate plant, which allows both lime-ammonium nitrate and sulfur-containing nitrogen fertilizers to be produced as an accompanying product of complex fertilizers. The high flexibility of this process makes it possible to adapt fertilizer production to the appropriate market situation in the shortest possible time.

The invention is explained in more detail below with several examples of its implementation with reference to the drawings, which depict:

- figure 1: schematically a first embodiment of a tubular reactor;

- figure 2: schematically a second embodiment of a tubular reactor;

- figure 3: schematically a third embodiment of a tubular reactor;

- figa: schematically two-component nozzle;

- figv: schematically granulation drum;

- figa: schematically a first variant of a cascade mixing head;

- figv: schematically a second variant of a cascade mixing head;

- Fig.6: schematically the first embodiment of the device;

- Fig.7: schematically the second variant of the device.

Example 1

Figure 1 shows a schematic modular design of a tubular reactor 1 in the first embodiment. The reactor 1 includes an inlet zone, first and second mixing paths 3 and an outlet zone 4. Three spiral mixers 15 with different directions of rotation are built into each mixing path 3.

In the inlet zone 2 there is a mixing head 5, an inlet pipe 6 for calcium nitrate tetrahydrate as a means for loading the first reagent into the inlet zone 2 and a first inlet pipe 7 for ammonia as a means for loading the second reagent in the inlet zone 2.

In the input zone after the mixing head 5 is located the inlet pipe 8 for sulfuric acid as a means for loading the reagent into the tubular reactor, and the tool 8 is made of two parts.

The second ammonia feed pipe 9 as an additional means for loading the reagent into the tubular reactor is located between the two mixing paths 3.

Between the mixing path 3 and in front of the exit zone 4 there is a tee 10 for sampling with a tap in combination with a thermocouple.

Using this device, 6.9 parts of a solution of calcium nitrate tetrahydrate at a concentration of 59% calcium nitrate were converted with 1 part ammonia and 3 parts concentrated sulfuric acid. The reaction product of the following composition was obtained: 45% calcium sulfate, 47% ammonium nitrate, 3% ammonium sulfate and 5% water.

Example 2

In another embodiment of the tubular reactor, an inlet pipe 8 for sulfuric acid is located between the two mixing paths 3. The pipe 8 here has a bent shape. The outlet of the pipe is located in the center of the cross section of the tubular reactor (figure 2). Spiral mixers 15 are also integrated in the mixing path 3.

Ammonia is dosed on the head through the inlet pipe 7, and a solution of calcium nitrate through the inlet pipe 6. Ammonia and calcium nitrate are first mixed on the first mixing path 3, then sulfuric acid is dosed through the bent inlet pipe 8. Due to this device, the exothermic reaction of sulfuric acid with ammonia is suppressed.

Using this device, it was possible to obtain the same reaction product as in Example 1. The reagent consumption was, however, significantly increased. In a pilot plant with a reactor with a diameter of 35 mm and a length of 1.3 m, a reaction product of up to 2 t / h was obtained. The temperature in the reactor was 125-130 ° C, the pressure loss was about 300,000 Pa. At the end of the reactor, the gas and liquid phases are separated, resulting in atomization of the reaction product.

Example 3

The third option (figure 3) contains only one mixing path 3. In the inlet zone 2 there is a mixing head 5, an inlet pipe 6 for a solution of calcium nitrate as a means for loading the first reagent into the inlet zone and a first inlet pipe 7 for ammonia as a means to load the second reagent into the input zone. Here, also, an inlet pipe 8 for sulfuric acid as a means for loading the reagent into the tubular reactor is radially located in the inlet zone after the mixing head 5, the means 8 being made in two parts.

Also here, ammonia is introduced into the reactor frontally through the inlet pipe 7. Calcium nitrate tetrahydrate is introduced through the inlet pipe 6 with a 90 ° offset to the inlet pipe 7. The mixing head 5 is followed by the supply of sulfuric acid through the inlet pipe 8. Mixing takes place on the mixing path 3 reagents, and here the mixing path 3 is equipped with static mixing elements. The straight pipe as the outlet zone 4 forms the outlet of the reactor.

Using this device, as in examples 1 and 2, it was possible to obtain the desired reaction product. Due to the additional installation of the air inlet pipe, even with a small flow rate, optimal atomization of the reaction product at the reactor outlet was achieved.

Examples 4 and 5

In the fourth embodiment, the exit zone 4 is made in the form of a two-component nozzle (figa). The nozzle is made in the form of two concentric pipes, and the outlet zone 4 is made in the form of a conically narrowed inner pipe 4a. The outer pipe 17 of the nozzle through an annular pipe with connecting fittings for compressed air is located on the inner pipe 4a with the possibility of longitudinal movement, with the outer pipe 17 extending along the length of the inner pipe. A steeper narrowing angle of the outer pipe 17 to the inner pipe 4a provides a variable distribution of compressed air at the mouth of the inner pipe, as a result of which the product, when dispersed as a result of this, is introduced into the granulation drum 16 through a two-component nozzle with different dispersion thus made.

A two-component nozzle at the outlet of the reactor reduces, on the one hand, pressure fluctuations and prevents, on the other hand, the release of water vapor in the reactor. Due to this, the pressure in the reactor is stabilized, since it is determined mainly by the vapor pressure of water at the product temperature achieved due to the heat of reaction.

When using a two-component nozzle, the resulting product has the following composition: 45-50 wt.% Ammonium nitrate, up to 46 wt.% Calcium sulfate, up to 5 wt.% Ammonium sulfate and up to 5 wt.% Water.

In the fifth embodiment, the tubular reactor 1 is located at the rear end of the granulation drum 16 operated in the direct flow (Fig. 4B).

The finished product is sprayed from the outlet zone 4 directly into the granulation drum 16 streamlined by air. This device ensures that the water vapor released at the outlet of the reactor is sucked out of the granulation drum immediately with exhaust air and prevents longer contact with the product.

The product hardened in the granulation drum 16 is removed as a finished product at the bottom of the granulation drum 16. Smaller product particles are removed on the head of the granulation drum 16 and again fed to it through the loop.

Examples 6 and 7

The sixth and seventh options in figa, 5B relate to the implementation of the static mixing elements 12 and the mixing head 5.

In both versions, flows of ammonia 7 and a solution of calcium nitrate 6 are introduced into the cascade mixing head 5, to which the intensive mixer 12 is directly connected. Due to the use of the cascade mixing head and the location of the intensive mixer, it is possible to shorten the entire mixing plant, since the intensive mixer 12 replaces one of the mixing tracts 3.

The entry zone is followed by only one mixing path 3, equipped, as in examples 1-3, with spiral mixing elements.

Examples 8 and 9

Figure 6 shows a block diagram of a nitrophosphate process in which a complex fertilizer of the NPK15-15-15 + 3S type is obtained, and from a calcium nitrate in a plant for the production of lime-ammonium nitrate, a sulfur-containing nitrogen-based simple fertilizer of the type “ammonium nitrate with sulfur”. This is a variant of the method and device.

While nitrophosphoric acid after the dissolution of natural phosphate is conventionally processed into a complex fertilizer, the calcium nitrate tetrahydrate obtained by dissolving the natural phosphate in a calcium ammonium nitrate production plant supplemented with tubular reactor 1 as a mixing apparatus (ammonizer) is converted by concentrated sulfuric acid when feeding ammonia. The resulting gypsum-containing suspension is pumped out, mixed with ammonium nitrate from pressure neutralization 13 (ie, the reactor) and granulated into “ammonium nitrate with sulfur” sulfur fertilizer.

In the Odda 20 apparatus, natural phosphate is dissolved in nitric acid, whereby solid calcium nitrate tetrahydrate is obtained. It is filtered off from nitrophosphoric acid, converted with sulfuric acid in an ammonizer 14 and neutralized with gaseous ammonia. The resulting suspension is mixed with ammonium nitrate and, after granulation, a complex fertilizer NPK15-15-15 + 33 is obtained.

Figure 7 shows a block diagram of a nitrophosphate process in which a complex fertilizer, sulfur-free lime-ammonium nitrate and sulfur-containing nitrogen simple fertilizer are obtained. This is another embodiment of the invention.

In a nitrophosphorus plant with two Odda lines 21, 22, two ammonization lines 1, 14 and two granulation lines on one of the lines, NPK type fertilizer is conventionally obtained in the traditional way, while the second ammonization line contains a tubular reactor 1.

In reactor 1 of the second line, sulfuric fertilizer is produced from part of the calcium nitrate that occurs when natural phosphate is dissolved with sulfuric acid and gaseous ammonia and ammonium nitrate is fed.

The second part of calcium nitrate in the conversion of lime nitrate and with ammonium nitrate from pressure neutralizer 1 is traditionally processed into sulfur-free lime-ammonium nitrate.

List of Reference Items

1 - tubular reactor

2 - entrance zone

3 - mixing path

4 - exit zone

5 - mixing head

6 - introduction pipe for calcium nitrate tetrahydrate

7 - the first introduction pipe for ammonia

8 - introduction pipe for sulfuric acid

9 - the second input pipe for ammonia

10 - tee for sampling

12 - static mixer

13 - pressure converter

14 - ammonizer

15 - spiral mixing element

16 - granulation drum

17 - an external pipe of a two-component nozzle

20 - Odd installation

21 - line A Odd

22 - line B Odda

Claims (37)

1. A method of producing sulfur-containing nitrogen fertilizers in a tubular reactor (1) containing at least one inlet zone (2) and at least one mixing path (3), wherein the tubular reactor (1) contains at least , one first means (6) for loading the first reagent and at least one second means (7) for loading the second reagent, located in at least one inlet zone (2), and at least one third means (8, 9) for loading at least one third reagent, the third means (8, 9) being located about at least one inlet zone (2), on and / or after at least one mixing path (3), wherein the calcium nitrate solution interacts in a tubular reactor (1) with sulfuric acid in the presence of ammonia and behind by granulating the resulting gypsum-containing suspension, a fertilizer is obtained, in which at the first stage a) the reagents a solution of calcium nitrate and / or in the form of a melt and NH ₃ are loaded into the inlet zone (2) of the tubular reactor (1) and mixed in the mixing head (5), and at the second stage b) sulfuric acid is loaded into the inlet zone (2) ribbed reactor (1) before the mixing path (3) in a mixing circuit (3) or after the mixing path (3) to form a gypsum-containing slurry. 2. The method according to claim 1, characterized in that the calcium nitrate solution occurs in the production of complex fertilizers by the nitrophosphate method. 3. The method according to claim 1, characterized in that the content of calcium nitrate in the solution of calcium nitrate is 55-65%, in particular 60%. 4. The method according to claim 1, characterized in that the water content of the reaction mixture upon exiting the tubular reactor (1) is less than 10%. 5. The method according to claim 1, characterized in that the loading of NH ₃ into the inlet zone (2) in the first stage a) occurs parallel to the axis of the tubular reactor, and the loading of the calcium nitrate solution at an angle of 90 °. 6. The method according to claim 1, characterized in that the ammonia is charged into the inlet zone (2) in the first stage a) at an angle less than 90 ° to the axis of the tubular reactor, and the calcium nitrate solution is loaded parallel to the axis of the tubular reactor. 7. The method according to claim 6, characterized in that in the third step c) additional ammonia is loaded into the tubular reactor (1) after at least one mixing path (3). 8. The method according to claim 6, characterized in that in the first stage a) at least 2/3 is loaded, and in the third stage c) at least 1/3 of the total amount of ammonia required. 9. The method according to claim 1, characterized in that the mixing of ammonia and a solution of calcium nitrate in the inlet zone (2) occurs by means of a static mixer, in particular an intensive mixer. 10. The method according to claim 1, characterized in that the mixing after adding sulfuric acid occurs on the mixing path (3) by means of a static mixing element (15), in particular a spiral mixing element. 11. The method according to claim 1, characterized in that the reaction temperature in the tubular reactor (1) is set to 120-145 ° C, preferably 130-140 ° C. 12. The method according to claim 1, characterized in that the reaction pressure in the tubular reactor (1) is 250,000-600,000 Pa, preferably 250,000-350,000 Pa. 13. The method according to claim 1, characterized in that after the mixing path (3) and / or between the mixing path (3) and the outlet zone (4), air is introduced into the tubular reactor (1). 14. The method according to claim 1, characterized in that before and / or during the conversion and / or before granulation, ammonium nitrate is added. 15. The method according to claim 1, characterized in that it is carried out continuously and it is integrated into the installation for the continuous production of complex fertilizers by the nitrophosphate method. 16. The method according to claim 1, characterized in that the tubular reactor (1) contains several means (8, 9) for loading the third reagent, moreover, the means (8) is located in at least one inlet zone (2), and means (9) - after at least one mixing path (3). 17. The method according to claim 1, characterized in that at least one mixing path (3) is located between at least one inlet zone (2) and at least one outlet zone (4). 18. The method according to claim 1, characterized in that the tubular reactor (1) contains at least two mixing paths. 19. The method according to p. 18, characterized in that at least one third means (8, 9) for loading the third reagent into the reactor is located between at least two mixing paths (3). 20. The method according to claim 19, characterized in that at least one third means (8, 9) for loading the third reagent is made between at least two mixing paths (3) in the form of a bent inlet pipe, and the output the opening of the inlet pipe is located in the center of the cross section of the reactor. 21. The method according to claim 1, characterized in that at least one third means (9) for loading the third reagent into the tubular reactor serves to load ammonia. 22. The method according to claim 1, characterized in that at least one third means (8) for loading the third reagent into the tubular reactor serves to load sulfuric acid H ₂ SO ₄ . 23. The method according to claim 1, characterized in that at least one third means (8) for loading sulfuric acid in the inlet zone (2) is made of at least two parts, the parts being located radially around the tubular reactor (one). 24. The method according to claim 1, characterized in that at least the first means (6) in the inlet zone (2) serves to load a solution of calcium nitrate, while at least the second means (7) in the inlet zone (2) serves for loading NH ₃ . 25. The method according to claim 1, characterized in that at least one inlet zone (2) contains at least one mixing head (5), in particular a cascade mixing head 27. 26. The method according A.25, characterized in that at least one static mixer, preferably an intensive mixer, is located in the mixing head (5) of the inlet zone (2). 27. The method according to claim 1, characterized in that the first means (6) for loading the first reagent into the inlet zone (2) includes an inlet pipe with a diameter of up to 40 mm. 28. The method according to claim 1, characterized in that the other means (7) for loading another, second reagent into the inlet zone (2) includes an inlet pipe, in particular a bent inlet pipe, with a diameter of up to 150 mm 29. The method according to claim 1, characterized in that the means (6, 7) for loading the first and second reagents into the inlet zone (2) are located at an angle of 0-90 °, preferably 90 °, to the axis of the tubular reactor. 30. The method according to claim 1, characterized in that the means (6, 7) for loading the first and second reagents into the inlet zone (2) are located at an angle of 0-180 °, preferably 90 ° to each other. 31. The method according to claim 1, characterized in that at least one mixing path (3) has at least one static mixing element (15). 32. The method according to p, characterized in that the static mixing element (15) comprises means for changing the direction of rotation of the flow, in particular a spiral mixing element, means for swirling, in particular an intensive mixer, and / or a static mixer. 33. The method according to claim 1, characterized in that the mixing path (3) has a diameter of up to 300 mm, in particular 50-250 mm 34. The method according to claim 1, characterized in that the total length of the mixing path (3) is from 5400 to 5500 mm, in particular less than 4000 mm. 35. The method according to 17, characterized in that the output zone (4) is directed to the granulation drum (16). 36. The method according to 17, characterized in that the outlet zone (4) has at least one nozzle, at least one narrowing and / or at least one conical narrowing. 37. The method according to 17, characterized in that between the mixing path (3) and the outlet zone (4) are at least one means (10) for sampling, in particular in the form of a tee, at least one means for determining the temperature and / or at least one additional means (11) for introducing air.

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